We present the plasmon-enhanced nonlinear nanofocusing of a gold (Au) nanoprism array substrate (ANAS) driven via an ultrafast azimuthal vector beam (AVB). Theoretical calculations show that the electric-field intensity of the ANAS vertically excited via the femtosecond AVB is higher than that of LPB excitation. In this experiment, the second-order surface nonlinear optical response of the ANAS is adopted to examine the nonlinear plasmonic nanofocusing of the ANAS, and it was observed that the second harmonic (SH) intensity of the ANAS excited via the femtosecond AVB is ∼3.8 times higher than that of LPB excitation, revealing that the ANAS under AVB excitation has a better nonlinear plasmonic nanofocusing characteristic than that under LPB excitation. Furthermore, the GaSe nanosheets are transferred on the ANAS to examine the nonlinear plasmonic nanofocusing of the ANAS. The SH intensity of the GaSe nanosheets deposited on the ANAS via the femtosecond AVB excitation has been enhanced ∼4.7 times than that of LPB excitation, indicating that the ANAS via AVB excitation has better nonlinear plasmonic nanofocusing than that of LPB excitation. This method may be used as a nonlinear nanofocusing light source to increase the light–matter nonlinear interaction.

中文翻译：

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通过超快速方位矢量束驱动的金纳米棱镜的等离子体增强非线性纳米聚焦

我们介绍了通过超快方位矢量光束（AVB）驱动的金（Au）纳米棱镜阵列基板（ANAS）的等离子体增强非线性纳米聚焦。理论计算表明，通过飞秒AVB垂直激发的ANAS的电场强度高于LPB激发的电场强度。在本实验中，采用了ANAS的二阶表面非线性光学响应来研究ANAS的非线性等离子体纳米聚焦，并观察到了ANAS的二次谐波（SH）强度通过飞秒AVB比LPB激发高约3.8倍，表明AVB激发下的ANAS具有比LPB激发下更好的非线性等离子体纳米聚焦特性。此外，GaSe纳米片被转移到ANAS上以检查ANAS的非线性等离子体纳米聚焦。沉积在所述ANAS纳米片GASE的SH强度通过飞秒AVB激励已增强比LPB激发的~4.7倍，表明ANAS通过AVB激励具有更好的非线性等离激元纳米聚焦比LPB激发的。该方法可以用作非线性纳米聚焦光源，以增加光-物质非线性相互作用。